Estimated richness and environmental correlates of miniature fish assemblages in the rio Jacundá, Brazil

Abstract South America is home to more miniature fishes (<26 mm in standard length) than any other continent. Despite this diversity, the ecology of miniature fishes is poorly studied. To promote the study of miniature fish ecology, we investigated patterns in total richness, assemblage structure and environmental correlates for miniature fishes in the rio Jacundá drainage of the Lower Amazon River basin, Pará State. Based on multi-pass dip-netting of leaf litter at 20 locations distributed across two sites, we collected miniature species and used rarefaction to estimate 9 to 14 species might be present. The miniature fish assemblage at the upstream site was a nested subset of the downstream site, and water pH and canopy cover, two features known to be altered by deforestation, correlated most strongly with assemblage variation. Our work represents one of the first quantitative assessments of environmental correlates with miniature fish assemblages and highlights research topics that should be investigated further to promote conservation and preservation of the overlooked and understudied Amazonian diminutive freshwater fish fauna.

摘要 南美洲拥有的微型鱼类（标准体长<26毫米）数量远超其他所有大陆。尽管该类群多样性丰富，但针对微型鱼类的生态学研究仍相对匮乏。为推动微型鱼类生态学研究，本研究针对帕拉州亚马逊河下游流域的雅孔达河（Rio Jacundá）流域内的微型鱼类，对其总物种丰富度、集合群落结构及环境关联因子模式展开了调查。研究团队在分布于两个采样点的20个点位开展枯落物层多遍扫网采样，收集到微型鱼类物种，并通过稀疏分析法（rarefaction）估算该区域可能存在9至14个物种。上游采样点的微型鱼类集合群落是下游采样点的嵌套子集，而水体pH值与冠层覆盖度这两个已知会因森林砍伐发生改变的环境因子，与集合群落变异的相关性最强。本研究是首批针对微型鱼类集合群落与环境关联因子开展的定量评估之一，同时明确了亟需进一步开展研究的方向，以推动对这片区域被忽视且研究不足的亚马逊小型淡水鱼类区系的保护与保育。